Heuchera americana

RHS Plant Profile
American alum root

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American alum root RHS

Other common names

American sanicle, rock geranium

Synonyms

Heuchera glauca

Herbaceous Perennial
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A mound-forming, evergreen perennial with rosettes of lobed, oval to heart-shaped, glossy leaves. Young foliage is marbled and veined brown, maturing to deep green with copper-green shading. Sprays of tiny, browny-green flowers on tall, upright stems appear in early spring

Position

Full sun, Partial shade

Soil Types

Clay, Loam, Sand

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
2–5 years
Max Spread
0.1-0.5 metres
Max Height
0.1-0.5 metres

Growing Conditions

Clay Loam Sand
Moisture
Moist but well–drained
pH
Neutral

Position

Full sun Partial shade
Aspect
East–facing or South–facing or North–facing or West–facing
Exposure
Exposed or Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

  • H1A: under glass all year (>15C)
  • H1B: can be grown outside in the summer (10 - 15)
  • H1C: can be grown outside in the summer (5 - 10)
  • H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
  • H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
  • H4: hardy through most of the UK (-10 to -5)
  • H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
  • H6: hardy in all of UK and northern Europe (-20 to -15)
  • H7: hardy in the severest European continental climates (< -20)
H6
Drought Resistance
Yes

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Saxifragaceae
Native to GB/Ireland
No
Foliage
Evergreen
Habit
Bushy
Genus
Heuchera are more or less evergreen, clump-forming perennials with attractive, rounded, shallowly palmately lobed leaves and racemes or panicles of small, tubular flowers, often with colourful calyces
Name Status
Correct
Plant Range
E USA

How to Grow

Cultivation

Grow in a fertile, moist but well-drained, neutral soil in sun or partial shade. The woody rootstock tends to lift out of the ground so mulch annually or lift and replant

Propagation

Propagate by seed sown in containers in autumn, or by division in autumn

Suggested planting locations and garden types

  • City and courtyard gardens
  • Coastal
  • Cottage and informal garden
  • Patio and container plants
  • Rock garden
  • Flower borders and beds
  • Underplanting of roses and shrubs

Pruning

Remove faded flower spikes

Pests

May be susceptible to leaf and bud eelworms and vine weevil

Diseases

May be susceptible to heuchera rust